1. FIELD OF THE INVENTION
The present invention relates to a laser working apparatus provided with a mechanism for scanning laser beam.
2. DESCRIPTION OF THE PRIOR ART
The conventional laser working apparatus using laser light scanning system has had a structure as shown in FIGS. 1 and 2. The laser working apparatus comprises, as shown in FIG. 1, a swingable mirror 2 driven by a drive mechanism (not shown) such as a galvanometer or an electric motor, and a convergence lens 3 for converging laser beam 1 reflected from the mirror 2 upon a work piece 4. The laser beam 1 emitted by the laser generator (not shown) is reflected and scanned by the swinging mirror 2. The scanned laser light is focussed through the convergence lens 3 upon the work piece 4, which is to be worked by the laser beam in a predetermined manner. In order to scan a laser light having a large diameter and to incise a work piece, the swing mirror 2 must be of the size enough to cover the beam size. However, such a large mirror necessarily has large inertia so that it is difficult in practical aspect to provide a drive mechanism for swinging the mirror having large inertia at high speed. Moreover, with the conventional laser working apparatus, if the positional precision in laser beam scanning must be improved, the hysteresis characteristic of the drive mechanism must be taken into consideration to control the swing motion of the mirror. Accordingly, there arises a drawback that the size of the drive mechanism is undesirably large while high technical level is needed in controlling the scanning of laser beam. Further, in the laser working apparatus as shown in FIG. 1, the laser beam is deflected through an angle twice as large as the angle of rotation of the mirror 2 so that if it is desired to scan the laser beam across a small interval, the rotational angle of the mirror 2 must be controlled within a small range. This leads to a technical difficulty.
The conventional laser working apparatus as shown in FIG. 2 comprises a convergence lens 5 for converging laser light 1, an X-Y table 6 which carries a work piece 4 along two axes, and two electric motors 7 to move the X-Y table 6 along the two axes. The laser beam converged through the lens 5 is relatively scanned with respect to the work piece 4 mounted on the X-Y table 6, by moving the table 6 along the two axes through driving the motors 7. In order to overcome the inertia of the table 6 and to subject the table to a smooth reciprocating motion, a motor having a large power must be provided. It is also practically difficult to reciprocate the X-Y table at high speeds. In addition, the laser working apparatus shown in FIG. 2 has a drawback that if it is desired to improve the scanning precision, the X-Y table 6 must be position-controlled with high accuracy.